The invention relates to lamps, more specifically reflector lamps with lenses.
Lenses are glued to reflectors in many reflector lamp configurations such as halogen and discharge lamps. Epoxy adhesives are typically employed to fix the lenses in place. Epoxies, however, have many limitations. Epoxies have limited life at elevated temperatures. They are relatively expensive, they discolor, and they are subject to both ozonolysis and radiative degradation. Among reflector lamps using epoxy adhesives to affix the lens, a substantial number of lenses have been reported to have fallen off of their lamps due to slow decay of epoxy strength and adhesion over time. Furthermore, epoxy adhesives become brittle upon cure, and embrittlement is exacerbated over time and through exposure to high temperatures during use.
Condensation-cure silicone adhesives have been used as a substitute for epoxy adhesives, but these adhesives generally have low green strength and low cured strength. Furthermore, condensation-cure silicone adhesives require long cure times and may produce corrosive byproducts during cure. Condensation-cure silicone adhesives also usually produce gaseous byproducts, which can result in gas bubbles being trapped in the adhesive layer, impairing the adhesive strength. It would be advantageous to utilize an adhesive for reflector lamps not subject to the limitations of epoxy and condensation-cure silicone adhesives.
A lamp comprises a reflector and a lens. The lens is secured to the reflector by an addition-cure silicone adhesive.